This invention relates to a polymeric material and to a process for preparing said polymeric material. More particularly, this invention relates to an elastomeric polymer which is modified to incorporate at least one conjugated diolefin linkage therein and to a process for preparing the same.
Elastomeric homopolymers and copolymer of various monomers are, of course, well known in the prior art. Moreover, polymers of this type having at least one active group comprising an alkali metal atom are also well known. In general, polymers comprising at least one alkali metal atom are prepared by polymerizing the monomers, either alone or in combination with other monomers, in the presence of an organometallic catalyst, wherein the metal is an alkali metal, particularly lithium, at a temperature within the range of from about -150.degree. C. to about 300.degree. C. Copolymers prepared in this manner may be block, tapered or random. Polymers of this type are described in a large number of references including, for example, U.S. Pat. Nos. 3,135,716; 3,150,209; 3,265,765; 3,231,635; 3,322,856; 3,496,154; 3,498,960; 4,145,298 and 4,298,202. It is also known in the prior art, that the reactive group or groups containing the alkali metal atom, particularly a lithium atom, may be reacted with various reagents to replace the alkali metal atom with a more stable reactive group. Such conversion is taught, for example, in U.S. Pat. Nos. 3,135,716 and 3,150,209. The reactive groups thus incorporated are said to facilitate curing through crosslinking or coupling.
It is also known in the prior art to incorporate one or more carboxyl groups into an elastomeric polymer and then using the thus modified copolymer in various applications, such as a modifier for thermosetting polyester resin compositions and in various other applications requiring polymers with adhesive properties. Incorporation of the carboxylic containing copolymer into polyester resin compositions may be via physical admixture as taught in the background sections of U.S. Pat. Nos. 4,439,438 and 4,400,478 as well as elsewhere in U.S. Pat. No. 4,329,438 or via chemical incorporation of the carboxyl containing polymer into the polyester as is taught in U.S. Pat. No. 3,892,819. In general, elastomeric homopolymers of conjugated diolefins and/or elastomeric copolymers of at least one conjugated diolefin and at least one other vinyl monomer, particularly an alkenyl substituted aromatic monomer, have, heretofore, been incorporated into thermosetting unsaturated polyester resin compositions in an effort to improve both the surface characteristics and the impact resistance of cured molded products. Physical incorporation of such thermoplastic modifiers has, however, heretofore frequently resulted in destructive phase separation of the components in the polyester resin composition and the properties of the cured products are frequently inferior to rather than superior to those obtained with a conventional polyester resin composition. The use of polymers comprising pendant carboxyl groups apparently reduces the negative results heretofore realized when a thermoplastic polymer was incorporated into an otherwise conventional thermosetting polyester resin composition but as indicated in the background section of U.S. Pat. No. 4,329,438 none of these approaches has been completely successful. The need, then, for an improved elastomeric modifier for polyester resin compositions is believed to be readily apparent.